1. Field of the Invention
The present invention relates to a paper separating apparatus of a printer for preventing the type of paper jam wherein a sheet of paper supplied to the printer is wound around and stuck to a transfer roller.
2. Description of the Related Art
In general, a printing apparatus, such as a printer or a photocopier, forms an electrostatic latent image on an optical photoreceptor such as a photosensitive drum or a photoreceptor web, develops the electrostatic latent image with developer having a predetermined color, and prints the developed image on a sheet of paper.
Referring to FIG. 1, a conventional printer includes a photoreceptor web 10 which circulates along an endless path while being supported by a plurality of rollers 11, 12 and 13, a main charger 20 disposed adjacent to the photoreceptor web 10 for uniformly charging the surface of the photoreceptor web 10 to a predetermined voltage, a laser scanning unit (LSU) 30 disposed adjacent to the photoreceptor web 10 for forming an electrostatic latent image of a desired image by scanning a laser beam onto the photoreceptor web 10, and a developing unit 40 disposed adjacent to the photoreceptor web 10 for developing the electrostatic latent image by using developer (i.e., ink) which is a mixture of powdered toner having a predetermined color and liquid carrier which is a solvent. For color printing, a plurality of the laser scanning units 30 and the developing units 40 are installed so that the electrostatic latent image can be developed for each of the colors, as shown in the drawing.
The image developed on the photoreceptor web 10 is dried by a drying roller 51 and heating rollers 52 to a state suitable for printing. Then, after being transferred to a transfer roller 61, the image is printed on a sheet of paper P which passes between the transfer roller 61 and a fusing roller 62. Each of the transfer roller 61 and the fusing roller 62 is heated by a predetermined heat source (not shown) so that the image is fixed on the paper P by being heated and pressed.
A paper separating apparatus 70, which guides a leading end of the paper P as it comes out from between the transfer roller 61 and the fusing roller 62 to prevent the paper P from being wound around the transfer roller 61, is installed at an exit side of the transfer roller 61.
However, as shown in FIG. 2A, since the paper P passing between the transfer roller 61 and the fusing roller 62 moves in contact with the upper surface of the paper separating apparatus 70, ink adhering to the paper P is detached from the surface thereof due to friction generated between the image fixed to the bottom surface of the paper P and the paper separating apparatus 70. The detached ink then accumulates on the upper surface of the paper separating apparatus 70. When the ink has accumulated on the upper surface of the paper separating apparatus 70 as described above, the accumulated ink may damage the image of a subsequent sheet of paper. Also, since a frictional force between the paper P and the paper separating apparatus 70 becomes greater, a smooth exit of the paper P is hindered so that a paper jam may occur.
Referring to FIG. 2B, the paper separating apparatus 70 can prevent the paper P from being wound around the transfer roller 61 only when the paper separating apparatus 70 is installed as close to the transfer roller 61 as possible. However, since the paper separating apparatus 70 is installed separated from the transfer roller 61, it is difficult to accurately maintain a gap having a distance D between the paper separating apparatus 70 and the transfer roller 61 due to the mechanical allowance thereof or allowance in installation. Accordingly, when the distance D is too short, the paper separating apparatus 70 may contact and damage the surface of the transfer roller 61 due to vibrations generated during the operation of the printer. On the other hand, the leading end of the paper P may enter and get caught in the gap of the distance D so that the paper P is wound around the transfer roller 61. Also, although the distance D is maintained appropriately, when an adhering force between the image fixed to the paper P and the transfer roller 61 is great, the type of paper jam wherein the paper P gets caught in the gap of distance D may occur because the paper is not separated from the transfer roller 61.
To solve the above problems, it is an object of the present invention to provide a paper separating apparatus of a printer which is improved to effectively prevent a paper jam wherein the paper is wound around the transfer roller.
Accordingly, to achieve the above object, there is provided a paper separating apparatus of a printer for preventing a paper jam from occurring when a sheet of paper which is passing between a transfer roller and a fusing roller of the printer is wound around the transfer roller, which comprises a separating member installed adjacent to an exit side of the transfer roller and under a path along which the paper is discharged and fixedly coupled to a pair of bearing guides which rotatably support opposite ends of the transfer roller to be operative to pivot by a predetermined angle together with the bearing guides, at least one guide roller installed at an upper surface of the separating member for guiding discharge of the paper, a pivot restricting mechanism which restricts a pivot angle of the separating member and the bearing guides, and an elastic force applying mechanism which applies an elastic force in one direction so that the separating member and the bearing guide can maintain regular positions. In the paper separating apparatus, when a pressure applied by the paper due to an adhesive force between the paper and the transfer roller to the upper surface of the separating member is greater than an elastic force applied by the elastic force applying mechanism, the separating member and the bearing guides pivot by a predetermined angle thereby overcoming the elastic force.
Also, to achieve the above object, there is provided a paper separating apparatus of a printer for preventing a paper jam from occurring when a sheet of paper which is passing between a transfer roller and a fusing roller of the printer is wound around the transfer roller, which comprises a separating member installed adjacent to one side of the transfer roller and under a path along which the paper is discharged and hinge-coupled to a pair of bearing guides which rotatably support opposite ends of the transfer roller to be operative to a pivot by a predetermined angle with respect to the bearing guides, at least one guide roller installed at an upper surface of the separating member for guiding discharge of the paper, a pivot restricting mechanism which restricts a pivot angle of the separating member, and an elastic force applying mechanism which applies an elastic force to the separating member in one direction so that a gap having a predetermined distance is maintained between a circumferential surface of the transfer roller and a surface of the separating member facing the transfer roller. In the paper separating apparatus, when a pressure applied by the paper due to an adhesive force between the paper and the transfer roller to the upper surface of the separating member is greater than an elastic force applied by the elastic force applying mechanism, the separating member pivots by a predetermined angle thereby overcoming the elastic force and an upper edge portion of the separating member approaches the surface of the transfer roller so that the gap is blocked and the paper is prevented from being caught in the gap.